Phylogeography and conservation genetics of the rare and relict Bretschneidera sinensis (Akaniaceae)

Abstract

Bretschneidera sinensis, a class-I protected wild plant in China, is a relic of the ancient Tertiary tropical flora endemic to Asia. However, little is known about its genetics and phylogeography. To elucidate the current phylogeographic patterns and infer the historical population dynamics of B. sinensis, and to make recommendations for its conservation, three non-coding regions of chloroplast DNA (trnQ-rps16, rps8-rps11, and trnT-trnL) were amplified and sequenced across 256 individuals from 23 populations of B. sinensis, spanning 10 provinces of China. We recognized 13 haplotypes, demonstrating relatively high total haplotype diversity (hT = 0.739). Almost all of the variation existed among populations (98.09%, P < 0.001), but that within populations was low (1.91%, P < 0.001). Strong genetic differentiation was detected among populations (GST = 0.855, P < 0.001) with limited estimations of seed flow (Nm = 0.09), indicating that populations were strongly isolated from one another. According to SAMOVA analysis, populations of B. sinensis in China could be divided into five geographic groups: (1) eastern Yunnan to western Guangxi; (2) Guizhou-Hunan-Hubei; (3) central Guangdong; (4) northwestern Guangdong; and (5) the Luoxiao-Nanling-Wuyi -Yangming Mountain. Network analysis showed that the most ancestral haplotypes were located in the first group, i.e., the eastern Yungui Plateau and in eastern Yunnan, which is regarded as a putative glacial refugia for B. sinensis in China. B. sinensis may have expanded its range eastward from these refugia and experienced bottleneck or founder effects in southeastern China. Populations in Liping (Guizhou Province), Longsheng (Guangxi Province), Huizhou (Guangdong Province), Chongyi (Jiangxi Province), Dong-an (Hunan Province), Pingbian (Yunnan Province) and Xinning (Hunan Province) are proposed as the priority protection units.

Demographic history and genetic differentiation of an endemic and endangered Ulmus lamellosa (Ulmus)

“…These results provided insights into the phylogeography and demographical history of U. lamellosa. However, chloroplast genes have a relatively slower evolutionary ratio than do nuclear genes, are generally of maternal inheritance, and cannot reflect pollen flow in angiosperms [41][42][43]. Furthermore, the results based on chloroplast genes provide only limited information on the phylogeographic structures and evolutionary history of plants, particularly intra-specifically [25,44].…”

An Akania (Akaniaceae) inflorescence with associated pollen from the early Miocene of New Zealand

“…Instead, the seeds of A. bidwillii are yellow to brown, smell strongly (Doweld, ), and are reported to be bird‐dispersed (Moran, ; Weber et al., ). The fruits and seeds have also been related previously on their anatomy to Bretschneidera (Doweld, ), but the red seeds of the latter are thought to be gravity‐dispersed and show low vagility, based on population genetic studies (Wang et al., ). It is likely that the fossil taxon was also avichorous, given the absence of mammals, apart from bats (Hand et al., , ) and the presence of frugivorous birds (e.g., Worthy et al., , , ) in Miocene New Zealand.…”

Advantage and Disadvantage of Global and Local Climate Datasets on Modeling Species Distribution at Continental and Landscape Scales

“…According to recent studies, most of the populations are seriously threatened (Hu et al 2014) and the species also suffers from reproductive failure due to low seed productivity and seed germination rates (Qiao et al 2012). Geographical range of the endangered species extents from Southern China to India, Indo China, Vietnam, and Taiwan (Dong et al 2019;Hu et al 2014;Kumar et al 2017;Li et al 2016;Wang et al 2018). Taiwan is a continental island possessed isolated population of B. sinenis at geographical margin of the Eurasia continent.…”

“…Bretschneidera sinensis Hemsl., a deciduous tree species of montotypic genera belongs to the family Akaniaceae, is a relic species of the Tertiary tropical ora mainly occurring in evergreen broad-leaved or mixed evergreen and deciduous forests in mountainous areas at altitudes of 300-1,700 m above sea level in Southern China (Dong et al 2019;Li et al 2016;Wang et al 2018). The species is listed as endangered on the IUCN Red List of Threatened Species (IUCN 2020, http://www.iucnredlist.org).…”

“…In this study, the WorldClim and local climate datasets were applied for RF and PCA to project potential distribution range and to construct climate space of the endangered plant species, Bretschneidera sinensis Hemsl. The endangered plant species is majorly distributed in Southern China and marginal populations of the species extend to Indo China, India and Taiwan (Dong et al 2019;Hu et al 2014;Kumar et al 2017;Li et al 2016;Wang et al 2018). Populations of the species are quiet small and have suffered from isolation and fragmentation of habitats (Dong et al 2019).…”